Mechanical time fuse



arch w, E946. F. 'r. CHRISTIAN 2,396,987

MECHANICAL TIME FUSE Filed Feb. 9, 1940 Patented Mar. 19, 1946 UNITE MECHANICAL TIlVIE FUSE Frank '1. Christian, Elmira, N.

Bendix Aviation Corporation,

Y., assignor to South Bend,

Ind., a corporation of Delaware Application February 9, 1940, Serial No. 318,125

2 Claims.

The present invention relates to a mechanical time fuse for projectiles and more particularly to improvements for insuring the release of the firil'lg. pin at the proper time either under service conditions or during static tests of the fuse.

'In mechanical time fuses as now constructed, it is customary to provide a firing pin for explodinga detonating cap, which pin is held in retracted position by a trigger or detent, the release of which is controlled by a timing mechanism.

The timing mechanism as usually constructed includes a pivotal latch having a lug bearing on the periphery of a rotatable timing disc and adapted. to enter a notch in the disc when in registry therewith, the lug being counterbalanced by a weighted projection on the latch movable by centrifugal force in a direction to cause the lug to enter the notch. Since the friction of the lug on the timing disc tends to impair the accuracy of the chronometric mechanism, it is desirable to keep the counterbalance weight as low as possible consistent with reliable operation of the latch. Moreover, it is desirable to subject fuses to various forms of static tests in which centrifugal force is absent.

It is an object of the present invention to provide a mechanical time fuse incorporating a novel device for assuring the operation thereof irrespective of the effects of centrifugal force.

It is another object to provide such a device incorporating a rotary latch which is counterbalanced as respects centrifugal force, with means for continuously biasing the latch toward released position irrespective of centrifugal effects.

It is another object to provide such a device having spring means for effecting release of the latch.

It is another object to provide such a device incorporating a lock for preventing release of the latch, with yielding means for holding said lock in operative position.

It is another object to provide such a device in which the spring releasing means for the latch serves also as the yielding holding means for the lock.

Further objects and advantages will be apparent from the following description taken in connection with the accompanying drawing in which:

Fig. 1 is a side elevation incorporating a preferred embodiment present invention;

Fig. 2 is a top plan View thereof;

Fig. 3 is a sectional view of the fuse mechof a fuse mechanism of the anism in a shell, the section being taken substantially on the line 3--3 of Fig. 1;

Fig. 4 is a view similar to Fig. 3 showing the parts in released position;

Fig.5 is a detail in perspective of the latch operating spring Fig. 6 is a View similar to Fig. 1 of a embodiment of the invention;

Fig. '7 is a section taken substantially on the line 1-1 of Fig. 6; and

Fig. 8 is a detail in perspective of the latch spring of the second embodiment of the invention.

In Figs. 1 and 2 of the drawing there is illustrated a known form of fuse having timing disc I adapted to be rotated by any suitable form of clockwork, not illustrated, in order to bring a notch 2 into registry with a lug 3 on a latch lever 4 journalled in the fuse frame 10. Axle 5 of latch G is provided with a milled section 6 arranged to accommodate the free end of a detent I pivoted at 8 in the frame. Detent I, as best seen in Fig. 3, is arranged to hold a firing pin 9 in retracted position against the action of a firing pin spring I I (Fig. 1) so long as the latch 4 is maintained in locking position as illustrated in Figs.- 1, 2 and 3.

According to the present invention, means are provided for insuring rotation of the latch 4 in a direction to release the firing pin detent i as soon as the lug 3 of the latch comes into registry with the notch 2 in the timing disc I. As here shown, this means is in the form of a spring member ll of suitable elastic material seated in second A the frame 10 and having a free end I3 adapted to bear against a pin l4 fixed in the axle 5 of the latch 4 to thereby constantly urge the latch in a direction to release the detent l.

A weight [5 is provided on the latch t to act as a counterbalance for the lug 3; This weight is preferably arranged to slightly overbalance the latch so that centrifugal force tends to move it to releasing position, The spring l2 may then be made only sufiiciently stifi to secure reliable operation of the latch in a static condition, centrifugal force during dynamic testing or in service being prevented from adversely affecting the operation of the device.

In operation, the parts of the fuse when set occupy the positions illustrated in Figs. 1, 2 and 3, the distance of the notch 2 from the lug 3 being the measure of the timing of the fuse. When the timing disc I is rotated by the clockwork to bring the notch 2 into registry with the lug 3, the spring I! is permitted to expand rotating the axle 5 of the latch into position where the milled section 6 is presented to the end of the detent I, The detent is thus freed for rotation on its pivot 8 to the position illustrated in Fig. 4, thereby releasing the firing pin in the usual manner.

In Figs. 6, '7 and 8 an embodiment of the invention is illustrated in which a safety lock for the latch 4 is provided, which look isialso. corrtrolled by the latch-releasing spring I221. here illustrated, a locking plunger [6 is slidably mounted in the frame H] of the fuse and is nor.--

mally positioned as shown in Fig, 6 where it engages the pin M of the latch 4 to positively prevent rotation of the latch in a releasing direction.

The plunger IB is provided with ataneredfpontion IT, and latch spring [2a is provided witht-a tongue 18 having a projection I 9 arranged to engage the tapered portion 1-1 and yi'eldingly maintain the plunger in its locking position,

When the projectile containing the fuse is discharged, or the fuse issubjected tonahcomparable' longitudinal acceleration, the plunger 16. is, set back by its inertia out of locking position against the resistance of the tongue IJB. of spring ma, whereupon the operation of the fusezmayrtake place as described in connection Withthe: first embodiment of the invention. a 7

Although certain embodiments of theinven- "for the latch normally engaging said projection slidablelout of locking position, and a spring having a portion cooperating with said projection .to urgenthe latclitoward releasing-position and V havinganother portion cooperating with the lock V to retain it in operative position.

Z-In-a mechanica b time fuse for projectiles, a firing pin, a pivotal trigger for holding the pin in inoperative position, a rotary latch for the trigger-having a, lateral projection, a slidable lock: forsaid latch cooperating with said projec. tion, and: a. spring: havingtwol arms, one-arm opposing movement: of the lock outv of locking position and the other arm. cooperating with. said projection-mo urge the-latch toward'released position,

T. CHRISTIAN; 

